The present invention relates to improvements of a caliper which constructs an opposed piston type disc brake used for braking an automobile. Particularly, the present invention realizes a structure for which while the weight is reduced, the vibration and noise produced in braking can be controlled by increasing the support stiffness of an outer body relative to an inner body, and a sufficient heat dissipation performance is secured.
Opposed piston type disc brakes are widely used for braking automobiles. When an automobile is braked by the disc brake, a pair of pads, which are arranged at both sides in an axial direction of the rotor which is rotated with a vehicle wheel, presses against the two side surfaces of the rotor with pistons. The axial direction refers to an axial direction of a rotor, and refers to the same in this specification. Various structures are known as the disc brake conventionally, but to obtain a stable braking force, the opposed piston type disc brake in which pistons are provided to be opposed to each other at both sides of the rotor is increasingly used recently. For example, a structure of a disc brake caliper is disclosed in Patent Document 1 in which an outer body and an inner body of the caliper are integrated, and while a temperature increase of pressure oil is controlled, the caliper can be well ventilated.
FIGS. 9 and 10 show an example of a traditional structure of the disc brake caliper described in Patent Document 1. The caliper 1 includes an inner body 2, an outer body 3, a pair of joining parts 4a, 4b and a reinforcing joining part 5. The inner body 2 is provided to be opposed to an inner side surface of a rotor (not shown in the figure) which is rotated with a vehicle wheel. The inner side refers to an inward side in a widthwise direction of a vehicle body in a state where the caliper is assembled to the vehicle, and refers to the same in this specification. The outer body 3 is provided to be opposed to an outer side surface of the rotor. The outer side refers to an outward side in the widthwise direction of the vehicle body in the state where the caliper is assembled to the vehicle, and refers to the same in this specification. The pair of joining parts 4a, 4b are provided outside of the outer circumferential edge of the rotor in a radial direction, and connects the both ends of the inner body 2 and the outer body 3 in a circumferential direction to each other. The radial direction refers to a radial direction of the rotor, and refers to the same in this specification. The circumferential direction refers to a circumferential direction of the rotor, and refers to the same in this specification. The reinforcing joining part 5 is also provided beyond the outer circumferential edge of the rotor in the radial direction to connect two central parts of the inner body 2 and the outer body 3 in the circumferential direction of the rotor to each other.
Furthermore, inner cylinders 6, 6 and outer cylinders are provided respectively at the surfaces, which face each other, of the inner body 2 and the outer body 3. Although only the inner cylinders 6 are recorded in FIG. 9, symmetrically, the outer body 3 is also provided with the outer cylinders which have the same shape as the inner cylinders 6 to sandwich the rotor. When the disc brake is assembled, the inner cylinders 6 and the outer cylinders are opened towards the inner side surface and the outer side surface of the rotor, respectively. At the time of braking, an inner pad which is supported by the inner body 2 is pressed against the inner side surface of the rotor by inner pistons which are oil tightly fitted in the inner cylinders 6, 6. Similarly, an outer pad which is supported by the outer body 3 is pressed against the outer side surface of the rotor by outer pistons which are oil tightly fitted in the outer cylinders. At the time of the braking, as a reaction when the inner pad and the outer pad are pressed against the two side surfaces of the rotor by the inner pistons and the outer pistons, a force is applied to separate the inner body 2 and the outer body 3 from each other. The reinforcing joining part 5 has a function of controlling the two bodies 2 and 3 from being elastically displaced in the direction away from each other irrespective of the force.
[Patent Document 1] JP-A-2010-078055